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securitycritical PriorityID: openfga-cdc-consistency-barrier-guardrail

OpenFGA CDC Eventual Consistency Barrier & Contextual Fencing

Enforces transactional fencing tokens and contextual tuple injection during authorization checks in distributed CQRS architectures. Prevents stale authorization exploits and unauthorized window execution caused by Change Data Capture (CDC) replication lag between the write model and OpenFGA tuple stores.

Prohibited Anti-Pattern: Unfenced OpenFGA Authorization Checks Subject to Asynchronous CDC Replication Lag

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---
description: OpenFGA CDC Eventual Consistency Barrier & Contextual Fencing - Enforces transactional fencing tokens and contextual tuple injection during authorization checks in distributed CQRS architectures. Prevents stale authorization exploits and unauthorized window execution caused by Change Data Capture (CDC) replication lag between the write model and OpenFGA tuple stores.
globs: src/auth/**/*.ts, src/services/**/*.ts, src/cqrs/**/*.ts, src/events/**/*.ts
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/openfga-cdc-consistency-barrier-guardrail"
---

# OpenFGA CDC Eventual Consistency Barrier & Contextual Fencing

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Unfenced OpenFGA Authorization Checks Subject to Asynchronous CDC Replication Lag

## System Constraints
You are a Principal Software Architect enforcing authorization consistency standards across distributed CQRS and event-driven engines using OpenFGA. Asynchronous CDC pipelines to OpenFGA create dangerous replication windows where revoked access or mutated ownership remains exploitable. You must enforce strict consistency barriers: authorization checks during sensitive command execution MUST incorporate transactional fencing tokens via OpenFGA Contextual Tuples or assert causal consistency boundaries against primary write-model metadata.

## Strict Guidelines
- Engineers MUST ALWAYS supply ephemeral Contextual Tuples representing the uncommitted or latest transactional state when executing checks within write/command paths.
- Engineers MUST NOT rely exclusively on persisted OpenFGA tuples for authorization checks immediately following state mutations in CQRS flows.
- Services MUST capture a monotonic fencing token (e.g., Postgres LSN, version number, or ULID) from the primary OLTP store and verify that CDC consumer watermarks meet or exceed this token before serving read queries without contextual tuples.
- Components NEVER permit critical state mutations (e.g., role revocations, tenant offboarding, asset transfers) to succeed without propagating real-time contextual overrides to concurrent or subsequent authorization queries.
- Code SHOULD implement an explicit fall-through or circuit breaker that fails closed when CDC lag exceeds defined SLAs and contextual validation cannot be computed.

## Bad vs Good Implementations
### Enforcing Contextual Tuples as a Consistency Barrier in CQRS Command Execution

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: The check relies solely on pre-existing tuples in OpenFGA. In distributed CQRS systems, CDC pipelines (e.g., Debezium to Kafka to OpenFGA writer) suffer non-deterministic replication delays. An adversary can execute commands within this delay window immediately after permission revocation.
```typescript
import { OpenFgaClient } from '@openfga/sdk';

interface TransferCommand {
  actorId: string;
  documentId: string;
  targetTenantId: string;
}

export async function handleTransferDocument(cmd: TransferCommand, fgaClient: OpenFgaClient): Promise<void> {
  // VULNERABILITY: Stale authorization check. If a preceding transaction revoked
  // cmd.actorId's permissions or modified tenancy, asynchronous CDC pipeline
  // replication lag to OpenFGA allows unauthorized access during the sync window.
  const { allowed } = await fgaClient.check({
    user: `user:${cmd.actorId}`,
    relation: 'can_transfer',
    object: `document:${cmd.documentId}`,
  });

  if (!allowed) {
    throw new Error('Forbidden');
  }

  // Executes critical mutation against OLTP store based on stale state
  await executeTransfer(cmd.documentId, cmd.targetTenantId);
}
```

#### Production Standard (Correct)
> **Standard**: Fetches authoritative versioning metadata from primary storage and provides OpenFGA with contextual tuples and context attributes. This guarantees that authorization evaluation is fenced by the authoritative state, preventing window exploits caused by CDC lag.
```typescript
import { OpenFgaClient, ClientCheckRequest } from '@openfga/sdk';
import { db } from '../database/client';

interface TransferCommand {
  actorId: string;
  documentId: string;
  targetTenantId: string;
  expectedMinimumVersion: number;
}

export async function handleTransferDocument(cmd: TransferCommand, fgaClient: OpenFgaClient): Promise<void> {
  // Read the authoritative fencing token and transactional state directly from OLTP
  const docRecord = await db.document.findUniqueOrThrow({
    where: { id: cmd.documentId },
    select: { version: true, ownerId: true, isBlocked: true, tenantId: true }
  });

  if (docRecord.version < cmd.expectedMinimumVersion || docRecord.isBlocked) {
    throw new Error('Precondition Failed: Stale state or entity blocked.');
  }

  // Inject contextual tuples representing the real-time authoritative OLTP boundary
  // to bridge CDC lag and close the race condition window.
  const checkRequest: ClientCheckRequest = {
    user: `user:${cmd.actorId}`,
    relation: 'can_transfer',
    object: `document:${cmd.documentId}`,
    contextualTuples: [
      // Immediate contextual barrier overriding eventual consistency state
      {
        user: `user:${docRecord.ownerId}`,
        relation: 'owner',
        object: `document:${cmd.documentId}`
      },
      {
        user: `tenant:${docRecord.tenantId}`,
        relation: 'parent',
        object: `document:${cmd.documentId}`
      }
    ],
    context: {
      is_blocked: docRecord.isBlocked,
      fencing_version: docRecord.version
    }
  };

  const { allowed } = await fgaClient.check(checkRequest);
  if (!allowed) {
    throw new Error('Forbidden: Unauthorized by OpenFGA barrier check.');
  }

  await executeTransfer(cmd.documentId, cmd.targetTenantId, docRecord.version);
}
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

OpenFGA Model & Tuple Inspector
Inspects authorization models and evaluates test assertions against OpenFGA tuple stores.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

OpenFGA CLI Toolkit
Command-line tool for model validation, tuple testing, and consistency verification.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: OpenFGA CDC Eventual Consistency Barrier & Contextual Fencing

OpenFGA CDC Eventual Consistency Barrier & Contextual Fencing defines an industrial-grade behavioral standard for security engineering. Enforces transactional fencing tokens and contextual tuple injection during authorization checks in distributed CQRS architectures. Prevents stale authorization exploits and unauthorized window execution caused by Change Data Capture (CDC) replication lag between the write model and OpenFGA tuple stores. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Unfenced OpenFGA Authorization Checks Subject to Asynchronous CDC Replication Lag Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftUnfenced OpenFGA Authorization Checks Subject to Asynchronous CDC Replication LagCritical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Engineers MUST ALWAYS supply ephemeral Contextual Tuples representing the uncommitted or latest transactional state when executing checks within write/command paths.

Engineers MUST ALWAYS supply ephemeral Contextual Tuples representing the uncommitted or latest transactional state when executing checks within write/command paths.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Engineers MUST NOT rely exclusively on persisted OpenFGA tuples for authorization checks immediately following state mutations in CQRS flows.

Engineers MUST NOT rely exclusively on persisted OpenFGA tuples for authorization checks immediately following state mutations in CQRS flows.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Services MUST capture a monotonic fencing token (e.g., Postgres LSN, version number, or ULID) from the primary OLTP store and verify that CDC consumer watermarks meet or exceed this token before serving read queries without contextual tuples.

Services MUST capture a monotonic fencing token (e.g., Postgres LSN, version number, or ULID) from the primary OLTP store and verify that CDC consumer watermarks meet or exceed this token before serving read queries without contextual tuples.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

Components NEVER permit critical state mutations (e.g., role revocations, tenant offboarding, asset transfers) to succeed without propagating real-time contextual overrides to concurrent or subsequent authorization queries.

Components NEVER permit critical state mutations (e.g., role revocations, tenant offboarding, asset transfers) to succeed without propagating real-time contextual overrides to concurrent or subsequent authorization queries.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

Code SHOULD implement an explicit fall-through or circuit breaker that fails closed when CDC lag exceeds defined SLAs and contextual validation cannot be computed.

Code SHOULD implement an explicit fall-through or circuit breaker that fails closed when CDC lag exceeds defined SLAs and contextual validation cannot be computed.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is OpenFGA CDC Eventual Consistency Barrier & Contextual Fencing critical for AI coding assistants?

Enforces transactional fencing tokens and contextual tuple injection during authorization checks in distributed CQRS architectures. Prevents stale authorization exploits and unauthorized window execution caused by Change Data Capture (CDC) replication lag between the write model and OpenFGA tuple stores. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Unfenced OpenFGA Authorization Checks Subject to Asynchronous CDC Replication Lag) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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